1. Field of the Invention
The invention herein relates to a wound dressing product, combining a hydrophobic fabric, facing towards the wound and being capable of binding unwanted micro organisms, together with a moisture holding material such as a gel or a foam or the like. The product is ideal for the treatment of drier wounds
2. Description of the Related Art
The problem in healing of wounds associated with high bacterial loads is, for example, tissue damage by release of toxins and enzymes and possible spread of infections to the blood stream. Studies have also shown that high tissue counts of microorganisms as well as dry wounds delay wound healing.
Numerous studies during the last few decades have also shown that bacteria, such as Staphylococcus aureus and Group A streptococci, both common wound pathogens, and the yeast Candida albicans, commonly express profound cell surface hydrophobicity. Several structures which render the cell surface hydrophobic have been defined, such as the fimbriae of E. coli which mediate adhesion to the intestinal wall, proteins on C. albicans which has been called “hydrophobins”, and lipoteichoic acid in the cell wall of Gram-positive bacteria.
According to the hydrophobic principle of the laws of nature, a system will always struggle towards lowest possible energy consumption. When two water repellent molecules come into collision with each other they will increase the entropy and create disorder. The water molecules that surround the two hydrophobic molecules will force them together by hydrogen bonds between the water molecules although there is no force of attraction between the hydrophobic interactions, and will expel water molecules.
The initial step of infections of the skin and mucosal surfaces is microbial adhesion to wounded tissues. Several microbial components that adhesively bind to specific receptors have been identified, such as fimbriae of Gram-negative enteric bacteria. Initial adhesion can be mediated by hydrophobic interactions between microbes and host tissue structures, and also by charge interactions. Binding of extra cellular matrix and serum proteins, like fibronectin, collagen and fibrinogen may further enhance colonization of deeper wound tissue.
In wound treatment, after tissue colonization, wound microbes multiply causing tissue damage by release of toxins and enzymes, and may even spread to the blood stream. The human body has multiple defense mechanisms, for example the innate defense system. Also specific antibodies directed against the colonizing microorganism may be active to decrease the number of microorganisms. Numerous studies have shown that high tissue counts of microorganisms delay wound healing. On the other hand, small numbers of bacteria were shown to enhance the wound healing process in rodents by stimulating production of collagen-hydroxyproline.
Conventional treatment of wounds consists of mechanical cleansing with water, buffer solutions or disinfectants to remove bacteria and debris. This is of importance since debris hampers wound healing. The use of oxidizing agents (for example iodine tincture) or antiseptics (for example ointments comprising silver sulphadiazine) have been known for a long time. A number of disadvantages to these methods can be mentioned. For example, bacteria which have died remain in the wound, and wounds cannot be cleaned to remove the active compound reliably after the application, since it spreads in the entire wound. If these active compounds occur freely in the wound, they can also attack cells and substances in the wound fluid which promote wound healing.
Another method of wound treatment is the use of local antibiotics. Microbiologists disapprove of the use of local antibiotics since this is known to induce antibiotic resistance. Also, in order to protect an already cleaned wound, including wounds from surgical cuts, various kinds of Band-Aid's, surgical tapes and dressings and the like have been used. Various kinds of cleaning and anti-microbial compounds added to such products been added or suggested for more long time effects.
A more modern and overall effective method (the so called Sorbact-principle) is the use of a product combining both a traditional dressing with a mounted absorbent material plus a hydrophobic fabric which is capable of binding unwanted microorganisms and is attached to the absorbent material and placed towards the wound, this is described in U.S. Pat. No. 4,617,326 and patent application WO2006/062470A1. Products containing pads of bacteria-binding fabric and absorbing fabric, to be held together and on a wound by a bandage or tape, already exist in the market. However the problem with such solutions being based on the hydrophobicity of unwanted microorganisms in the wound and their binding ability to the integrated hydrophobic fabric of the dressing, is that they require a certain amount of moisture for the hydrophobic binding to occur. This is not a problem in most cases as wound fluids are available, but in some special cases, for example foot-wounds of diabetics or other dry wounds there is a need for additional moisture.
A diabetic foot ulcer is an open sore or wound that most commonly occurs on the bottom of the foot in approximately 15 percent of patients with diabetes. Of those who develop a foot ulcer, six percent will be hospitalized due to infection or other ulcer-related complication.
Diabetes is the leading cause of nontraumatic lower extremity amputations in the United States, and approximately 14 to 24 percent of patients with diabetes who develop a foot ulcer have an amputation. Anyone who has diabetes can develop a foot ulcer. Native Americans, African Americans, Hispanics and older men are more likely to develop ulcers. People who use insulin are at a higher risk of developing a foot ulcer, as are patients with diabetes-related kidney, eye, and heart disease. Being overweight and using alcohol and tobacco also play a role in the development of foot ulcers.
Ulcers form due to a combination of factors, such as lack of feeling in the foot, poor circulation, foot deformities, irritation (such as friction or pressure), and trauma, as well as duration of diabetes. Patients who have diabetes for many years can develop neuropathy, a reduced or complete lack of feeling in the feet due to nerve damage caused by elevated blood glucose levels over time. The nerve damage often can occur without pain and one may not even be aware of the problem. Your podiatric physician can test feet for neuropathy with a simple and painless tool called a monofilament.
Vascular disease can complicate a foot ulcer, reducing the body's ability to heal and increasing the risk for an infection. Elevations in blood glucose can reduce the body's ability to fight off a potential infection and also retard healing.
Foot ulcers in patients with diabetes should be treated for several reasons such as, reducing the risk of infection and amputation, improving function and quality of life, and reducing health care costs. The primary goal in the treatment of foot ulcers is to obtain healing as soon as possible. The faster the healing, and reduced number of unwanted microorganisms in the wound, the less chance for a problematic infection. For optimum healing, ulcers, especially those on the bottom of the foot, must be “off-loaded.” Patients may be asked to wear special footgear, or a brace, specialized castings, or use a wheelchair or crutches. These devices will reduce the pressure and irritation to the ulcer area and help to speed the healing process.
The science of wound care has advanced significantly over the past ten years. The old thought of “let the air get at it” is now known to be harmful to healing. We know that wounds and ulcers heal faster, with a lower risk of infection, if they are kept covered and moist. The use of full strength betadine, peroxide, whirlpools and soaking are not recommended, as this could lead to further complications.
There are several known inventions relating to the use of antimicrobial substances and materials. One such example is the U.S. Pat. No. 6,369,289, which discloses the use of a cellulosic bandage in a method for covering an open wound by contacting the wound with the bandage having a calculated amount of antimicrobial agent. The disclosure of this patent and all other patents referred to herein is incorporate herein by reference. U.S. Pat. No. 4,655,756, relates to a non-woven material treated with a linear polymeric biguanide having a defined formula, or a mixture of, e.g., polyhexamethylene biguanide (PHMB).
Other types of antimicrobial agents are also known. For example, U.S. Pat. No. 5,707,736 discloses a dry, disposable, polymeric product having sustained-release antimicrobial activity that is formed from a polymeric material having an amine salt antimicrobial agent incorporated therein. The polymeric material may be in the form of fibbers, sheets, films, and other stable woven, nonwoven and knitted materials. The antimicrobial agents include, e.g., chlorhexidine gluconate and chlorhexidine hydrochloride. Several similar uses of dressings combining antimicrobial compounds are known.
U.S. Pat. No. 4,678,704 describes an impregnated fabric material comprising a fabric substrate to which has been applied an active cationic impregnate along with an anionic indicator dye in combination with a further cationic component, wherein the dye bonds to the further cationic component more readily than to the substrate and the further cationic component competes with the impregnated for bonding to the dye. The cationic imp regnant may be a polymeric biguanide.
U.S. Pat. No. 5,098,417 relates to a wound dressing for systemic administration of a physiologically- or biologically-active agent by controlled release of the agent into such wound. The wound dressing comprises a substrate in the form of a fabric or cloth, at least a portion of which is cellulosic, which has been chemically modified to convert hydroxyl groups in the cellulosic portion to ionic-adsorbing sites, an ionic form of a physiologically- or biologically-active agent (which includes antibacterial agents) adsorbed in the substrate. The ionic bonds hold the agent temporarily to the substrate for controlled release therefrom in proportion to the amount of exudate in contact with the substrate and are formed by adsorbing the agent on the substrate at room temperature. The ionic bonds are disassociated upon contact with body exudate from wounds thereby to release the physiologically- or biologically-active agent in an amount in proportion to the amount of exudate in contact with the substrate.
U.S. Pat. No. 5,700,742 relates to a method of treating a textile material to inhibit microbial growth, which comprises applying to the textile material an oligo or polymeric biguanide or salt thereof with an inorganic acid or an organic acid having a pK value above 4.5 followed by a strong organic acid having a pK value below 4.5 and free from any aliphatic or oxyalkylene chain containing 12 or more carbon atoms. A textile material treated in accordance with the claimed method is also disclosed.
U.S. Pat. No. 5,856,248 relates to cellulose fibers and products comprising cellulose fibres treated to absorb body secretions while substantially decreasing microbial growth, the fibres being chemically modified in a two-stage process comprising a first stage treatment with a water soluble salt of a transition metal and an alkali and a second stage treatment with a solution of a bisbiguanide compound, thereby forming a bond between the cellulose fibres, the transition metal and the compound. The process may utilize a rinsing step to neutral pH between the two aforementioned stages.
U.S. Pat. No. 5,817,325 relates to an article of manufacture having disposed on a surface thereof a contact-killing, non-leaching antimicrobial coating that kills microorganisms upon contact. The coating comprises an organic polycationic polymer matrix immobilized on the surface having bound or complexed thereto a surface-accessible antimicrobial metallic material such that the antimicrobial material does not release biocidal amounts of elutables into the surrounding environment.
Other patents relate to the so-called SORBACT® products, which are folded dressing compositions including a hydrophobic fabric and a hydrophilic, liquid-absorbing material. U.S. Pat. No. 4,617,326 describes this principle. Further, U.S. Pat. No. 6,160,196 relates to the same principle but adds thereto an antimicrobial active compound which is adapted to prevent infections from the outside of the pad, the antimicrobial compound is not be released into the wound. U.S. Pat. No. 4,211,227 discloses a non-woven surgical sponge material comprising a layered fabric having an inner core or a substantially hydrophilic material disposed adjacent at least one outer or surface layer, or between a pair of outer layers, of a substantially hydrophobic material. The sponge material is bonded by passing the material through rolls engraved in a pattern of lands and grooves such that a repeating pattern of three degrees of compression are imposed on the material. However, the so produced sponge is using polyester fibres as the hydrophobic material, consequently the hydrophobic properties to bind microbes is not as effective as in the invention herein. Nor does the invention have the moisturizing properties as in the invention herein.
Since all microbes as well as viruses are negatively charged U.S. Patent application 2006/0163149 relates to an electrostatic method for absorption purposes. This application discloses an in water insoluble support matrix wherein the support matrix is substituted with a hydrophobic entity which in turn is connected to a positively charged entity. The invention also relates to a product for absorption purposes comprising a first support matrix connected to a hydrophobic entity and a second support matrix connected to a positively charged entity. Further the invention also relates to a product for absorption purposes comprising a support matrix wherein the support matrix is substituted with a hydrophobic entity and a positively charged entity. However the inventors do not discloses the moisturizing effect of the present invention.
U.S. Patent application 20040082925 describes a medical dressing containing an antimicrobial agent. The medical dressing comprises a layered fabric comprising an inner layer of substantially hydrophilic material, an outer layer of substantially hydrophobic material on both sides of the inner layer. Unlike the invention herein the applicants use an antimicrobial agent. Also they do not mention the moisturizing effect of the present invention.
Utilizing the so-called SORBACT® principle discussed above, products such as the SORBACT® pad consist of acetate gauze and cotton gauze treated with the fatty acid ester, for example DACC (dialkyl carbamoyl chloride) or an AKD (alkyl ketene dimer). This provides Sorbact pads with a strong hydrophobic property. When the Sorbact pad comes in contact with pathogenic microorganisms in the wound surface, the microorganisms adhere to the pad through hydrophobic interaction. The method is based on the principle that two hydrophobic surfaces bind to each other, when getting in physical contact. The SORBACT® pad consists of two components. The first component has one or more liquid permeable layers of a hydrophobic, bacteria adsorbing, physiologically innocuous material containing a woven or nonwoven hydrophilic fabric. The fabric has been rendered hydrophobic by chemical treatment with a compound containing hydrophobic groups. The second component consists of one or more layers of a hydrophilic, liquid adsorbing, physiologically innocuous material. The hydrophilic liquid absorbing material effects a liquid flow by suction of exudate from the wound. If the microorganisms exhibit hydrophobic surface structures they will accompany this flow of liquid and come in contact with the hydrophobic component and bind.
Even if the traditional SORBACT® pad product solves an important problem of reducing the number of microorganisms in a wound without using chemicals or antibiotics, however the problem with such solutions being based on the hydrophobicity and/or electrostatic solutions, (such as described in U.S. Patent application 2006/0163149) of unwanted microorganisms in the wound and their binding ability to the integrated hydrophobic and/or electrostatic fabric of the dressing, is that they require a certain amount of moisture for the hydrophobic binding to occur. This is not a problem in most cases as wound fluids are available, but in some special cases, for example foot-wounds of diabetics or other dry wounds there is a need for additional moisture.
Now, therefore the invention herein was made to address the above problems. It is an object of the invention herein to provide an integrated product ideal for the treatment of wounds, especially drier wounds, and a method of making this product. It is a further object of the invention to in an integrated fashion provide a product that protects the wound, absorbs exudate and reduces the number of pathogenic microorganisms, without using antimicrobial substances and adding moisture to the wound both supporting the hydrophobic functioning of the dressing and healing in general by keeping the wound moist.